Scott, your ears are tricking you into thinking your car is having to work harder to achieve the same speed. It has happend to many people before you and you won't be the last. You just need to get used to the new sound so give it a few weeks.

Sure it is possible. Also very possible that after a few days of driving it feels normal again. Sometimes changes can take the calibration away from perfection, and after a few hundred miles of it self adjusting can feel normal again. Also can be just a perception. With no exhaust sound before, you may have been pushing on the throttle harder and not realized it.

Ok talked with Ted at Jannetty Racing, he said yep I killed it. The resonator has perferations in the pipe and acts like a H-Pipe/X-Pipe. Said I lost some TRQ and HP something to do with balancing the sides of the engine. So went back to and just had X-Pipe put on. She is spinning rubber again like a wild child.

So will drive her today and see how she is, just hope I do not get a bad drone or buzz from AFM. It did quiet her down some, but she still sounds mean.

put in an x-pipe where the large resonator was,,, when i still had factory mufflers on mine and i took out the resonator and had a custom x-pipe made the car ran way better.

that factory resonator actually acts like a very inefficient h-pipe ,, if you look inside it, both banks come together then exit, so when you straight piped it you lost all the h-pipe/x-pipe exhaust effect